The present invention relates generally to an apparatus for testing a data multiplex transmission system by simulation of the terminal devices of the multiplex system. More particularly, the present invention relates to an apparatus for testing data multiplex transmission networks and systems that is capable of simulating the actual use conditions of communications between the computers and other terminals connected to the data multiplex system.
Before the present invention was developed, it was necessary to test the data multiplex system Input/Output modules and the associated functions of the multiplex system by using one of the computers of the system to provide data to the transmission bus of the system and a second computer of the system to receive it. The problems encountered in testing the multiplex system in this manner were inadequate for the following reasons. First, a different software package was required for each type of computer involved with the multiplex system. Developing this software was a time consuming and expensive procedure. The only practical method of testing the software was to use the multiplex system under test which led to extreme difficulty in sorting out the problems encountered. Since the computers operating through the multiplex system themselves were used to provide these test functions, high cost computer time was lost. Further, since one of the multiplex system computers was controlling the test operation, when an error occurred it was difficult to determine where the error occurred since such error might have been produced by misoperation of the computer itself.